In the field of compulsory automatic exchange of tax information, the European regulation has undergone a rapid evolution over the past five years, with the introduction of various guidelines on the administrative cooperation (CAD guidelines), which have planned a wider scope of European institutions replacement, with regard to controlling activities management and to national tax assessment, to enact subsidiarity and proportionality principle. Therefore, we have a gradual shift from a simple exchange process to a real sharing of important tax information, thanks to the creation and increasing implementation of computer systems and common European database, managed by the Commission, which go towards the creation of a new "European Tax Administration". The author investigates the regulation theoretical principles and the process which allowed its success, highlighting the critical points that came out in the Italian and European headquarters.